1. Field of the Invention
The present invention generally relates to an apparatus, system, and method for removing sediment from water, and, more particularly, to an elongated filtratable element used for removing sediment from stormwater.
2. Description of the Related Art
Stormwater runoff is rainfall or snowmelt that travels over the ground or impervious surfaces—roofs of buildings, homes and sheds, roadways, parking lots, sidewalks and driveways—and drains into natural or manmade drainage ways. In some cases, stormwater runoff drains directly into bodies of water. Stormwater runoff does not usually receive any treatment before it enters streams, lakes, and other surface waters, and it is a major source of water pollution. For example, various harmful pollutants, such as pesticides, fertilizer, litter, car oil, bacteria, trace metals, and sediment, are washed off with stormwater runoff into storm drains, or directly into streams, rivers, and lakes.
One of the harmful pollutants of major concern is sediment. Sediment is soil particles from stream banks, construction sites, and other areas, that are dislodged by stormwater runoff and deposited into streams, lakes, and rivers. Sediment accumulates in water bodies and destroys feeding grounds for aquatic life, clogs fish gills, blocks light, increases water temperature, and can cause other adverse environmental impacts.
Currently, sedimentation-based tanks are used to remove the majority of sediment that is dislodged by stormwater runoff. Sedimentation-based tanks, however, cannot completely remove all of the fine sediment from stormwater because of the required settling time needed for fine sediment to be removed from stormwater. For example, settling out the fine sediment in stormwater would require a large and uneconomical sedimentation-based tank. Therefore, in addition to sedimentation-based tanks, granular media filter systems are used downstream of sedimentation-based tanks to remove fine sediment. Granular media filter systems utilize different types of granular media to trap fine sediment in the interstitial gaps formed between the granular media. However, as the fine sediment continues to accumulate, the interstitial gaps eventually clog and must be frequently recharged. Granular media filter systems can be partially recharged through pressurized backwashing, but pressurized backwashing piping and controls are complicated and expensive.
In addition to granular media filter systems, a variety of other filter systems are available for filtering contaminated fluids. For example, filter cloths consisting of pile threads may be used, U.S. Pat. No. 6,103,132, which is incorporated by reference herein. While these types of filters and others like them have their merits, they also have their drawbacks. For example, the filters have a small amount of surface area available for trapping fine sediment. As a result, during high flow events, the filter systems quickly clog, causing the stormwater runoff to back up. In addition to filter cloths, flexible hose-type filter elements have been used, U.S. Pat. No. 4,163,724, which is incorporated by reference herein. Such hose-type filter elements, however, rely on pressurized flow to effect separation.